diff options
| -rw-r--r-- | include/drm/gpu_scheduler.h | 78 |
1 files changed, 47 insertions, 31 deletions
diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h index 6381baae8024..1a7e377d4cbb 100644 --- a/include/drm/gpu_scheduler.h +++ b/include/drm/gpu_scheduler.h @@ -383,8 +383,15 @@ struct drm_sched_job { struct xarray dependencies; }; +/** + * enum drm_gpu_sched_stat - the scheduler's status + * + * @DRM_GPU_SCHED_STAT_NONE: Reserved. Do not use. + * @DRM_GPU_SCHED_STAT_NOMINAL: Operation succeeded. + * @DRM_GPU_SCHED_STAT_ENODEV: Error: Device is not available anymore. + */ enum drm_gpu_sched_stat { - DRM_GPU_SCHED_STAT_NONE, /* Reserve 0 */ + DRM_GPU_SCHED_STAT_NONE, DRM_GPU_SCHED_STAT_NOMINAL, DRM_GPU_SCHED_STAT_ENODEV, }; @@ -447,43 +454,52 @@ struct drm_sched_backend_ops { * @timedout_job: Called when a job has taken too long to execute, * to trigger GPU recovery. * - * This method is called in a workqueue context. + * @sched_job: The job that has timed out + * + * Drivers typically issue a reset to recover from GPU hangs. + * This procedure looks very different depending on whether a firmware + * or a hardware scheduler is being used. + * + * For a FIRMWARE SCHEDULER, each ring has one scheduler, and each + * scheduler has one entity. Hence, the steps taken typically look as + * follows: * - * Drivers typically issue a reset to recover from GPU hangs, and this - * procedure usually follows the following workflow: + * 1. Stop the scheduler using drm_sched_stop(). This will pause the + * scheduler workqueues and cancel the timeout work, guaranteeing + * that nothing is queued while the ring is being removed. + * 2. Remove the ring. The firmware will make sure that the + * corresponding parts of the hardware are resetted, and that other + * rings are not impacted. + * 3. Kill the entity and the associated scheduler. * - * 1. Stop the scheduler using drm_sched_stop(). This will park the - * scheduler thread and cancel the timeout work, guaranteeing that - * nothing is queued while we reset the hardware queue - * 2. Try to gracefully stop non-faulty jobs (optional) - * 3. Issue a GPU reset (driver-specific) - * 4. Re-submit jobs using drm_sched_resubmit_jobs() - * 5. Restart the scheduler using drm_sched_start(). At that point, new - * jobs can be queued, and the scheduler thread is unblocked + * + * For a HARDWARE SCHEDULER, a scheduler instance schedules jobs from + * one or more entities to one ring. This implies that all entities + * associated with the affected scheduler cannot be torn down, because + * this would effectively also affect innocent userspace processes which + * did not submit faulty jobs (for example). + * + * Consequently, the procedure to recover with a hardware scheduler + * should look like this: + * + * 1. Stop all schedulers impacted by the reset using drm_sched_stop(). + * 2. Kill the entity the faulty job stems from. + * 3. Issue a GPU reset on all faulty rings (driver-specific). + * 4. Re-submit jobs on all schedulers impacted by re-submitting them to + * the entities which are still alive. + * 5. Restart all schedulers that were stopped in step #1 using + * drm_sched_start(). * * Note that some GPUs have distinct hardware queues but need to reset * the GPU globally, which requires extra synchronization between the - * timeout handler of the different &drm_gpu_scheduler. One way to - * achieve this synchronization is to create an ordered workqueue - * (using alloc_ordered_workqueue()) at the driver level, and pass this - * queue to drm_sched_init(), to guarantee that timeout handlers are - * executed sequentially. The above workflow needs to be slightly - * adjusted in that case: - * - * 1. Stop all schedulers impacted by the reset using drm_sched_stop() - * 2. Try to gracefully stop non-faulty jobs on all queues impacted by - * the reset (optional) - * 3. Issue a GPU reset on all faulty queues (driver-specific) - * 4. Re-submit jobs on all schedulers impacted by the reset using - * drm_sched_resubmit_jobs() - * 5. Restart all schedulers that were stopped in step #1 using - * drm_sched_start() + * timeout handlers of different schedulers. One way to achieve this + * synchronization is to create an ordered workqueue (using + * alloc_ordered_workqueue()) at the driver level, and pass this queue + * as drm_sched_init()'s @timeout_wq parameter. This will guarantee + * that timeout handlers are executed sequentially. * - * Return DRM_GPU_SCHED_STAT_NOMINAL, when all is normal, - * and the underlying driver has started or completed recovery. + * Return: The scheduler's status, defined by &enum drm_gpu_sched_stat * - * Return DRM_GPU_SCHED_STAT_ENODEV, if the device is no longer - * available, i.e. has been unplugged. */ enum drm_gpu_sched_stat (*timedout_job)(struct drm_sched_job *sched_job); |